If you need to complete the JGTC series, then the Xanavi Nismo GT-R (JGTC) & the Woodone Tom's Supra (JGTC) are probably the best choices, I say that because the prize car for that series is the Motul Pitwork Z (JGTC) which is the quickest, but its easy enough to win that series in any of the other JGTC 500 cars.